OK, hands up – who’s nicked Shane MacGowan’s gun? MacGowan’s widow Victoria Mary Clarke is not happy and she wants it back now, sparking a widespread search after tweeting: “Shane’s 1916 rifle has gone missing, most likely been stolen.”

The gun is not any old gun. It’s a rifle from the 1916 Easter Rising, and was probably used in the takeover of the General Post Office (GPO) by armed groups of the Irish Volunteers and the Citizen Army, commanded by Padraig Pearse and James Connolly. It was given to MacGowan as a 60th birthday present by the singer-songwriter Glen Hansard.

Clarke is devastated. Over the phone, she says it’s hard enough living without the former Pogues frontman, who died last November aged 65 of pneumonia, but for the rifle to disappear has just added to her pain. She’d like it returned ASAP – no questions asked. She only noticed it was missing on Wednesday, but she hasn’t got a clue how long it’s not been there. “I looked everywhere, turned the place upside down and couldn’t find it. So it has actually gone.”

Clarke asks me if I remember seeing it when I interviewed MacGowan at their house a couple of years ago. I don’t, I say, but I’m sure I would have if I’d seen it. She says it was between the fireplace and the bookshelf and well camouflaged. “I tend not to tidy up very much. I don’t spring clean, which means that for ages I don’t notice what’s there and what’s not.”

She sends me a photo of MacGowan in his famous green chair looking straight ahead, crucifix gleaming against his black top, rifle in hand ready to shoot. To be honest, when I see the picture I imagine myself on the other end of it. My interview with MacGowan wasn’t the easiest. “God these questions are fucking … ” he said at one point. He never quite got the last words out, but odds on they weren’t going to be “great” or “incredibly intelligent”. Despite that, we got on well afterwards.

The rifle, which was standard British army issue, is a Lee-Enfield 303 and has the name H Munn etched on it. During the Easter Rising, the GPO on O’Connell St in Dublin was the headquarters of the Irish Volunteers who took it over and proclaimed the Irish Republic, holding out for a week before surrendering to the British forces. The gun was probably seized by the rebels and used on both sides. During the uprising 485 people were killed, more than half of them civilians. Sixteen of the rising’s leaders were executed including Pearse and Connelly.

The rifle is thought to be valued at about £2,000-£3,000, but the emotional value for Clarke is incalculable. “The thing about Shane is that he wasn’t materialistic. The only things he ever bought really were records. He didn’t have many possessions. He had his crucifix and rosary beads and statues of the Virgin Mary, other than that he didn’t have possessions that were precious to him. But the gun meant so much to him. I wasn’t entirely easy about having it in the house, but I definitely want it back. It’s probably the grief, where any physical thing that has an attachment to your loved one you hold on to – because you want to hold on to them.”

• If you have any information about Shane MacGowan’s gun, please contact the Guardian